Generally, tube filling machines operate intermittently. The resulting index movement requires a highly efficient fixation of individual tubes in their support members during the transport in the machinery. For instance the following steps may be classified as important fixation considerations:
The input--the pushing down of a tube in a support member should be easy to carry out for eliminating deformation.
After the tube has been pushed down in the support member, the tube is not allowed to slide in the support member because positioning of the tube, i.e. rotation of the tube along the longitudinal axis thereof, takes place by rotating the entire support member, generally by a step motor.
The tube is not allowed to "tilt" in the support member when indexing--if this occurs, the tube will be damaged easily--buckled, especially after filling because the tube is easily deformed due to the index motion forces.
The tube should be safely fixed in the support member when lifting, for instance for filling the tube and for hot air end sealing. If the tube is not safely fixed in the support member, it will be necessary to use specific grip claws or vacuum support in the lift head.
The support member should allow a tube shape change when flattening the tube after it has been filled at the tube cap distal end.
It should be easy to push out or lift the entire support member at the output end of the machine.
Previously, attempts have been made to satify the just mentioned list of requisites in a number of different ways.
One simple method has made use of a pipe as the support member and the upper portion of the pipe is made conical for the accommodation of the flattening of the tube by the support member as far as possible.
The next step in the development chain has been to insert squeeze jaws in the support members and push such jaws inwards by means of externally placed spiral springs.
Another approach has been to use soft support members of some type of formable rubber quality that allows sliding movement when pushing the tube outwards and inwards.
Special type of support members have also been designed and have a counter sunk lower portion for placing the gravitation center at the level of the conveyor chain in order to decrease the tilting torque at the index movement.
Internal radial rings of different types represent further alternative means used.
However, the list of requisites listed above cannot be met fully by the prior art technique known within the field.